Boat superstructure



FIG. 1 is a side view of an embodiment of the boat superstructure design;

FIG. 2 is a top view of the boat superstructure design;

FIG. 3 is a frontal perspective view of the boat superstructure design; and,

FIG. 4 is a rear perspective view of the boat superstructure design. 

The ornamental design for a boat superstructure, as shown and described. 